SEM observations of the reactions of the components of a light-activated glass polyalkenoate (ionomer) cement on bovine dentine

Objectives: Glass ionomer cements are used in clinical dentistry as lining, luting and restorative materials. The precise nature of their bonding mechanism to dentine is unclear. This study is an SEM examination of the effect of the liquid contained in Vitrebond cement (3M Co., MN) on the surface of bovine dentine, with respect to delays in photocuring and washing off with water under pressure or as a gentle stream. The effects of delaying photocuring of the mixed and applied cement for up to 120 s were also examined. Results: The results of this study demonstrated that the liquid component of Vitrebond reacts chemically with dentine in a manner suggestive of an effervescent chemical reaction. This reaction produces plugs in the dentinal tubules which are resistant to dislodgement by water under pressure or by gentle washing. Similarly, a delay in photocuring the mixed and applied cements results in porosity of the cement at the dentine interface. Conclusion: The findings in this study suggest that the adhesion of Vitrebond to dentine is primarily chemical in nature and that its mechanical strength is compromised if there are substantial delays in photocuring.